Posted
by
samzenpus
on Wednesday June 11, 2014 @07:44PM
from the take-me-to-your-leader dept.

First time accepted submitter sayhem (1842674) writes Various explanations for why we don't see aliens have been proposed—perhaps interstellar travel is impossible or maybe civilizations are always self-destructive. But with every new discovery of a potentially habitable planet, the Fermi Paradox becomes increasingly mysterious. There could be hundreds of millions of potentially habitable worlds in the Milky Way alone. This impression is only reinforced by the recent discovery of a "Mega-Earth," a rocky planet 17 times more massive than the Earth but with only a thin atmosphere. Previously, it was thought that worlds this large would hold onto an atmosphere so thick that their surfaces would experience uninhabitable temperatures and pressures. But if this isn't true, there is a whole new category of potentially habitable real estate in the cosmos.

Well, it is always possible we are simply the first. We do have an unusually old population I star and it still took billions of years for humans to come on the scene, so it is possible that the typical case simply takes longer and many suns are younger then our's.

It's meaningless.Space is REALLY BIG. In fact, space s bigger than time is long.You could have started sending out robots 12 billion years ago and they wouldn't have even made a scratch in colonizing the universe.

You know what? All very nice, but how about this? We are not all that interesting, nor special, and in the last 35,000 years when we could comprehend what we're looking at, no-one's bothered to swing by and ask for a cup of sugar.

It may also be possible that we are part of a nature preserve, or that there are more than enough planets with similar conditions to inhabit, to not have to displace or destroy an entire culture.

Another possibility is that we're left alone, because other civilizations have been contacted before, and once given technology, have self immolated themselves akin to giving firearms to the natives.

That, or we're won the interstellar lottery, and we are indeed the first who will learn a lot of lessons as we swarm across the galaxy once we figure out how to get off this damn rock.

Maybe travel at the speeds necessary to reach other star systems is impossible, and there ARE a TON of civilizations out there. But, they're all talking on some type of communication form - like Quantum CB or something - that we haven't discovered quite yet.

One day we will, and we won't make first contact with ONE species that day. We'll meet millions.

So far, we have precious little evidence one way or another about this. Lots of people make up all sorts of numbers for the Drake equation, but frankly it's almost entirely speculation. There seems to be this assumption nowadays that life will inevitably evolve on planets with similar conditions to Earth, but how do we possibly know that? What counts as sufficiently "similar"?

Go back before Carl Sagan and a few other such scientists, and the idea that the cosmos was littered with life was treated only by imaginative science fiction writers -- the presumption that something like SETI should turn up something would have been seen a little weird, certainly not based on any scientific evidence.

And what evidence exactly have we accumulated since then? Other than 40 years of Star Trek finding civilizations everywhere, do we have anything scientific to base our estimates on?

No. Not really. In particular, while there has been some work in self-organizing systems and theories about how we get from basic amino acids to the first "living" cells, there's a whole lot of steps to fill in to explain how life begins.

And frankly, until we sort that out, let's just not pretend we're doing anything other than speculating from a single data point -- which means we have absolutely no evidence at all to decide whether the universe is teeming with life in every star system, or whether the situation on Earth was so specific that we're alone (or nearly so).

These articles about the Fermi Paradox always bother me a bit because of this. There's nothing "scientific" about them. I'm not saying we shouldn't look for aliens (and it would be truly interesting if we found anything), but we simply have no clue whether life is likely to evolve on 1 in 10 planets or 1 in 100 trilllion planets. Until we find life somewhere else or we can figure out the details of how to manufacture it in a lab (and determine how likely such conditions are to occur naturally), this is all idle speculation. Thus, there's really no "paradox" to resolve, since the probability estimates are meaningless.

First off, forget Hitler's Munich Olympics broadcast, that's way to new. The most interesting thing about Earth is roughly half a billion years old, and that's its "unnatural" atmosphere. Our atmosphere shouts, "Life!" like nothing else. The stuff in our air just doesn't cohabit from ordinary chemical processes - it has to be maintained. Not as old, but still older than Hitler's broadcast is the sustained presence of pollutants in the atmosphere. This might suggest, "intelligent, if immature/foolhardy life."

We can almost see this kind of stuff with Kepler, though to get to this level of detail we use several instruments in parallel - Kepler is the first-weeder. We're nowhere near having interstellar technology, so any race that does will likely have commensurate technologies in other areas as well. Most notably, if you're going to travel far, you want to know which direction to go, and as much about your destination as you can. They would have tools that make Kepler look like a child's toy. They would know how interesting Earth is. Where that ranks us with respect to other planets in another question, but I'll bet it's not as bleak a prospect as some say.

Personally I think the presence of us on Earth has to do with it's "sufficiently interesting history", including the collision that formed the moon, several asteroid/comet strikes like the dinosaur killer, etc. Not to mention plate tectonics, the magnetic field that keeps the solar wind from blowing our atmosphere away, etc. Like I said, I think Earth would be on the short-list.

By the same token, I also think they would observe. Our society and existence are fragile enough, one big kick could easily topple the whole mess. Imagine a preemptive strike by one power to prevent another power from getting "the advantages of alien technology," etc. We're also pretty darned "memetically susceptible," and even allowing an alien idea to reach us might upset the apple cart.

Or as an alternative, perhaps the Catholic Church was right, and Galileo (and Copernicus) were wrong. If not the physical center of the universe, if we're all there is, perhaps the Earth is the philosophical center of the universe.

So:1 - We're all there is, perhaps to become the Progenitors, perhaps not.2 - There is other life, hasn't gotten here yet, may not bother, may not be able.3 - There is other life, observing us, careful to remain unknown - the Prime Directive.4 - There is other life, getting ready to invade/destroy us.5 - There is other life, in contact only with the Illuminati and Club of Rome.

A civilization in a galaxy the size and structure of our own, expanding at an average of 0.1% of lightspeed, could still colonize every habitable planet in that galaxy in 100 million years. 0.1% of lightspeed is only about 20 times faster than Voyager 1 is currently moving, and well under the theoretical limit for a nuclear pulse drive. And 100 million years is not that long compared to cosmological and evolutionary timescales.

We are not all that interesting, nor special, and in the last 35,000 years when we could comprehend what we're looking at, no-one's bothered to swing by and ask for a cup of sugar.

Or it could be that interstellar travel is just extremely expensive, so that any aliens civilizations that exist either don't bother, or they can only afford to visit a small number of places (and we're way down the list), or they can only send extremely small (read: hard-to-notice) spacecraft.

Until we invent something like a Warp Drive (or at least discover a reason to think such a thing might be possible even in principle), I'm inclined to prefer this explanation, at least over the 'nature preserve' idea:)

Maybe travel at the speeds necessary to reach other star systems is impossible,

50% of light-speed would get you to the next solar system, in the same time it would take to get a university degree. From there, you or your offspring can choose to try again, and see what's on the next one.

You don't need exotic technology to colonize the universe... only if you want to jump from one to the next as easily as you visit your relatives, in fine, Hollywood-movie fashion.

This was already considered in the Fermi Paradox. It's fascinating to see how many people here obviously don't know it, yet are happy to chime-in on the subject.

and there ARE a TON of civilizations out there. But, they're all talking on some type of communication form - like Quantum CB or something - that we haven't discovered quite yet.

We're already on the verge of manipulating the heavens, moving small bodies where we want them. Where's the astronomical observations showing planets stacked-up in spots they couldn't possibly get-to, naturally? Where's the data showing a large dark, low-mass object, that could possibly be a Dyson Sphere? If there's lots of somebodies, more advanced than us out there, there should be some physical evidence that's practically visible from here.

The old biology rule is: if you have a sample of one, you make the assumption that it is "average."

Yes, I'm very familiar with this assumption. In exobiology arguments it's known as the principle of mediocrity [wikipedia.org].

The problem is that it's simply an assumption. It can be wrong. We simply don't know. Moreover, in biology this often makes a little more sense when you're, say, dealing with a single fossil specimen or something. In that case, you're at least dealing with an interdependent ecosystem of life, and based on evolutionary principlles, most specimens we encounter are likely to be ones that survived and multiplied and existed as species with more than one exemplar.

There's no such data or evidence for extraterrestrial life, because we're not part of a common ecosystem with known evolutionary principles. Again, we have just one data point.

There are 88 objects (known) in our solar system larger than 200 miles in diameter. We know one has life, we believe 3 others have a promising chance to have life (Enceladus, Titan. Europa), as well as the possibility of subterranean life on Mars (methane venting).

Based on what, exactly? A whole truckload of assumptions about how common life MUST be and what conditions make it LIKELY. But we have no evidence for most of those assumptions. Call me when you find life on one of those places with a "promising chance" -- then we'll have EVIDENCE to talk about and more than one data point. Until then, this is idle speculation.

So lets do some math.

There's only one number that matters: P (chance of life evolving on a random planetary body).

Do you know that number? I certainly don't. You can make a bunch of stuff up about how "unique" or "not unique" the Earth is, but you simply don't know.

You do the math on how many objects that are out there. Again, anyone who doesn't think the odds are there's any life out there don't understand how fucking big an "out there" it is.

The universe could have 10^100 planets in it that are earthlike, but it wouldn't mean crap about finding life if P (chance of life evolving on a random planetary body) is 10^200. You still can't estimate a probability from one data point.

This all reminds me of a discussion in Richard Dawkins's Blind Watchmaker. He talks about how unusual it would be for four players to simultaneously get a royal flush in poker (or something like that). And then he says -- let's imagine some creatures that lived for millions of years (I can't remember the exact amount, but he gives something more specific). And he then concludes -- with all that time playing poker, these creatures would obviously not find it unusual if they all drew royal flushes at the same time occasionally.

It's a fun argument, but just for kicks I actually ran the numbers, and it turns out that Dawkins was off by many orders of magnitude for the lifespans of these creatures in order for this occurrence to be likely for them to experience.

Dawkins was obviously being sloppy there, and I don't fault him a lot for it since he was just making a casual analogy -- but his flawed methodology is PRECISELY what you are doing here. He simply assumed, "Yeah -- creatures who live millions of years" and assumed the numbers would make it likely for the poker hand to show up. Except the number that matters is P(weird poker situation), and he obviously didn't bother to compare that to his hypothetical giant lifespans of these long-lived poker-playing creatures.

It doesn't matter how big the numbers are for things in the universe. What matters is the chance of life evolving. Do I think it's likely we're unique in the universe? Well, if I had to state my BELIEF, I'd say "no." But that's NOT SCIENCE.

Science says we have one data point, and there's nothing else to extrapolate fro

Which is utterly irrelevant to GP's point that we don't have the foggiest idea what the odds are of life arising. Our single, solitary sample isn't statistically significant.

There are several steps from amino acids to space-faring civilizations, and even active attempts by our best scientists haven't been able to get past step 1 in a controlled lab.

And in our one sample of life on Earth, we don't have any evidence in all of Earths history, of any of the steps happening TWICE, independently. Instead, it's all a nice, neat, clean, singular and unbroken, tree.

I don't know how likely it is, and NEITHER DO YOU. We have no idea what values belong in that part of the Drake Equation, and they could each/all conceivably be astronomically large.

One detail you miss is that when each step happens once, it reduces the probability of the same kind of step happening again locally, because the first occurrence is a competitor for the would-be second, and has a time advantage to have evolved to be a better competitor, or an assimilator. Remember, life is about pattern competition, and pattern amalgamation (if more effective than competition at prolonging the sub-patterns.)

Life is about information patterns competing with each other to pattern the matter and energy which both surrounds and hosts the information.

Probably quite likely to happen, so long as there is enough structural and functional vocabulary (molecular variety and molecular combination variety) for embodied information to have probable mechanisms for enacting their 3D printing. Oh and just enough thermodynamic free energy and gravity so that stuff comes together about as often as it blows apart. Oh and another probable requirement is a region (such as but not exclusively) Earth's surface region, where common elements exist in all three of gaseous, liquid, and solid form and can sometimes transition in phase. This latter condition is again part of ensuring there can be enough structural and functional vocabulary to make the mechanisms (containment in solid or semi-solid structure, flow of energy-transferring and material-transferring contained gases and fluids.)

I see Bob Lazar. I see Steven Greer. Anyone actually curious about the UFO phenomenon should not look at those.

For more serious stuff:- Belgium 1990 UFO flap- Tehran 1974 UFO- Rendelsham Forest- The age old Betty and Barney Hill case is still goodand if you are patient, read something written by people like John Mack or even Bruce Maccabee.

But the OP has a point. Aliens might be around, even when they have not landed on the White house lawn.